Frequencies for p4 variable in miper dataset :

         p4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        557       68.09       68.09
          1 |          1        0.12       68.22
          2 |          7        0.86       69.07
          3 |          7        0.86       69.93
          4 |          9        1.10       71.03
          5 |          3        0.37       71.39
          6 |          1        0.12       71.52
          7 |          4        0.49       72.00
          8 |         10        1.22       73.23
          9 |         14        1.71       74.94
         10 |          8        0.98       75.92
         11 |          8        0.98       76.89
         12 |         14        1.71       78.61
         13 |         12        1.47       80.07
         14 |          9        1.10       81.17
         15 |         15        1.83       83.01
         16 |         11        1.34       84.35
         17 |         13        1.59       85.94
         18 |          7        0.86       86.80
         19 |         19        2.32       89.12
         20 |          9        1.10       90.22
         21 |          5        0.61       90.83
         22 |         11        1.34       92.18
         23 |          8        0.98       93.15
         24 |          7        0.86       94.01
         25 |          6        0.73       94.74
         26 |          4        0.49       95.23
         27 |          5        0.61       95.84
         28 |          9        1.10       96.94
         29 |          6        0.73       97.68
         30 |          2        0.24       97.92
         31 |          5        0.61       98.53
         32 |          3        0.37       98.90
         34 |          1        0.12       99.02
         36 |          3        0.37       99.39
         37 |          2        0.24       99.63
         39 |          1        0.12       99.76
         41 |          2        0.24      100.00
------------+-----------------------------------
      Total |        818      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016